The present disclosure relates to image forming apparatuses such as copiers, facsimile machines, and printers, and to removable developer containers incorporated in such image forming apparatuses. More particularly, the present disclosure relates to an opening/closing mechanism for a developer discharge port in developer containers that feed developer by rotation of the container body.
Conventionally, for easy maintenance, development devices incorporated in image forming apparatuses are filled with predetermined amounts of developer (toner) and, when the developer runs out, the whole development devices are replaced. For an economical point of view, however, frequent replacement of developing devices is impractical, and accordingly, to permit image formation on a satisfactorily large number of sheets, there is no choice but increase the capacity of developer. This makes the just-mentioned method unsuitable for size reduction. For the size reduction of developing devices, therefore, there have been proposed developer containers, such as toner containers and toner cartridges, that are provided separately from developing devices, and developing devices of the type that feeds developer by use of a developer feeding mechanism such as an intermediary hopper.
Known methods of feeding developer to a developing device includes one according to which developer is fed from a developer container where it is contained directly to the developing device, and one according to which a developer container is coupled to a developer feeding mechanism and developer inside the developer container is stirred and transported by the developer feeding mechanism to as to be fed from a predetermined position to the developing device. Also known is a technology according to which no stirring/transporting member is used but a developer container itself is rotated to transport developer to a desired position.
A method relying on rotation of a developer container itself eliminates the need to provide a stirring/transporting member inside the developer container, and thus has the advantages of increasing the amount of developer that can be contained in the developer container and reducing the cost of the developer container. In addition, the developer is then not subjected to the rotating load of the stirring/transporting member during transport, and is thus saved from deteriorating under mechanical stress.
Inconveniently, however, a method relying on rotation of a developer container itself as described above has the disadvantage that, when the developer container is connected or removed, the developer may leak through a developer discharge port formed in the developer container. This may lead to contamination of the maintenance person and the inside of the image forming apparatus with the leaked toner, and thus adversely affects the ease of handling and maintenance.
As a solution, there have been proposed developer containers that are easy to handle, without the risk of developer leakage, and easy to replace. For example, in one known toner container, a toner container holding member that has an inner wall which makes contact with a toner discharge port in a toner containing portion in a predetermined position to close the toner discharge port is provided so as to be movable, by a feed screw mechanism, relative to the toner container body in the rotation axis direction of the toner container body.
In this toner container, when the toner container body is rotated relative to the toner container holding member in the direction reverse to the rotation direction for toner discharge out of the toner containing portion, the toner containing portion and the inner wall of the toner container holding member come into contact with each other, and thus the toner discharge port is closed. When the toner container body is rotated relative to the toner container holding member in the rotation direction for toner discharge out of the toner containing portion, the toner containing portion and the inner wall of the toner container holding member come apart from each other, and thus the toner discharge port is opened.
With the construction described above, removing the toner container with completely no toner inside the toner container body proceeds with no problem. On the other hand, removing the toner container with toner remaining inside the toner container body may result in, while the toner container body is rotated in the reverse direction to close the toner discharge port, toner being caught between the toner containing portion and the toner container holding member. This hampers smooth operation of the feed screw mechanism which waves the toner container holding member relative to the toner container body, and thus, if the toner container is removed with the toner discharge port closed incompletely, toner may leak.